\(\frac{5}{{38}}\) là tích của hai phân số nào:
\(\begin{array}{l}
\left( A \right)\frac{{ - 5}}{2}.\frac{1}{{ - 19}}\\
\left( B \right)\frac{{ - 5}}{{-19}}.\frac{1}{2}\\
\left( C \right)\frac{5}{{ - 2}}.\frac{{ - 1}}{{19}}\\
\left( D \right)\frac{1}{{ - 2}}.\frac{5}{{19}}
\end{array}\)
\(\begin{array}{l}
\left( A \right)\frac{{ - 5}}{2}.\frac{1}{{ - 19}} = \frac{{ - 5.1}}{{2.\left( { - 19} \right)}}\\
= \frac{{ - 5}}{{ - 38}} = \frac{5}{{38}}\\
\left( B \right)\frac{{ - 5}}{{19}}.\frac{1}{2} = \frac{{ - 5.1}}{{19.2}} = \frac{{ - 5}}{{38}}\\
\left( C \right)\frac{5}{{ - 2}}.\frac{{ - 1}}{{ - 19}} = \frac{{5.\left( { - 1} \right)}}{{ - 2.\left( { - 19} \right)}}\\
= \frac{{ - 5}}{{38}}\\
\left( D \right)\frac{1}{{ - 2}}.\frac{5}{{19}} = \frac{{1.5}}{{ - 2.19}} = \frac{{ - 5}}{{38}}
\end{array}\)
Chọn A
-- Mod Toán 6
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